A&P Nervous system (senses)

Senses are responsible for…

Monitoring and sharing info in and out of bodies

Categories of senses

• general

• Special

General senses

Receptors found throughout the body, including skin,

organs, and joints

Special senses

Receptors confined to structures in the head

Sensory information triggers a _____ which sends the signal a long a _________ to the CNS where the info is _______

• Receptor

• Sensory nerve

• CNS

• Interpreted/processed

Main receptor types

• Chemoreceptors

• Nociceptors

• Thermoreceptors

• Mechanoreceptors

• Photoreceptors

Chemoreceptors

Chemical concentrations

Nociceptors

Pain through tissue damage

Thermoreceptors

Temperature changes

Mechanoreceptors

shape-changes

Proprioceptors

muscle and ligament tension

Baroreceptors

pressure

Stretch receptors

inflation/deflation

Photoreceptors

Light intensity

Sensation

When a sensory neuron reaches threshold and the sign,a makes it to the brain.

Perception

the bodily/conscious awareness of a sensation after it is been interpreted by the brain

Sensory adaptation

• ignoring unimportant sensory info.

• Prevents overwhelming the brain with sensory

  information

Special senses

give us specific information about our environment

Types of special senses

• Olfaction

• Gustation

• Hearing

• Vision

Olfactory organ

chemoreceptors located on the anterior side of the ethmoid bone with extensions into the nasal cavity

Extension divided in layers called

Lamina propria

Olfactory epithelium

Lamina propria

Areolar tissue, blood vessels, nerves, mucous glands

Olfactory epithelium

• Provide base for cilia

• Holds olfactory receptors (10-20 million/5 cm2)

Taste receptors

chemoreceptors located on the surface of the tongue and adjacent parts of the pharynx and larynx

Taste buds

hold groups of cells that open to the surface

Major flavors

• sour

• Bitter

• Sweet

• Salty

• Umami

Hair cells

mechanoreceptors located in the inner ear

Regions ear is divided into

• external

• Middle

• Inner

External ear

Catches and directs sound waves

Middle ear

• Air-filled chamber separated from the external ear by

the tympanic membrane (eardrum)

• Holds auditory ossicles

Inner ear

Contains sensory organs for hearing and equilibrium

External ear (pt)

• Auricle/Pinna

• External acoustic meatus

• Tympanic membrane

Middle ear (pt)

• Auditory/Eustachian tube

• Auditory ossicles

• Muscles

Auditory ossicles

• Malleus

• Incus

• Stapes

Malleus

Attaches to the tympanic membrane

Incus

Attaches to the malleus to the stapes

Stapes

Attaches the middle ear to the inner ear at the oval window

Muscles (pt)

Tensor tympani, stapedius

Tensor tympani

attaches at the temporal bone and the malleus; contraction stiffens the tympanic membrane and reduces the amount of vibration

Stapedius

attaches at the back of the middle ear and the stapes; contraction pulls the stapes and reduce a movement as the oval windows

Stereocilia

hair-like extensions extend into the cochlear duct

Layers of inner ear

Bony labyrinth

Membranous labyrinth

the outer bony labyrinth and the inner membranous labyrinth, make up these areas

• Semicircular canals

• Vestibule

• Cochlea

Semicircular

Rotation and equilibrium

Vestibule

Gravity and linear accelerator

Cochlea

Hearing; the hair cells are below and anchored in the tectorial membrane

Photoreceptors

located in the eyeball; sensitive to light

What are photoreceptors covered by…

Internal and external structures

External structures are…

Accessory structures

Examples of external structures

• eye lids

• Eyelashes

• Conjunctiva (epithelium that covers the eye)

• Lacrimal apparatus

Eye lid

protects eye; blinking lubricates and removes debris

Eyelashes

prevent foreign objects from entering

Conjunctiva

mucous membrane with stratified squamous epithelium

Lacrimal apparatus

produces, distributes, and removes tears

Internal structures

Eye wall

Examples of internal structures

• Fibrous tunic (outer)

• Vascular tunic (middle)

• Neural tunic (inner)

Outer

Cornea & sclera

Fibrous tunic

Provides some protection, muscle attachment site, holds the cornea

Middle

Iris & ciliary muscle & chiroid

Vascular tunic

Provide routes for blood and lymph supply, regulate light, secrete and reabsorb aqueous humor, control shape of the lens (focusing)

Inner

Retina

Neural tunic

Absorbs light, contains photoreceptors

Changes in what, determines the degree of vision

The lens shape

Rounds lens

Close vision

Flattened lens

Distance vision